 ;; proper temporal comparison of two unrelated datasets.
 
 (ns forma.date-time
-  (:use [clj-time.core :only (date-time plus month year days)]
+  (:use [clj-time.core :only (now date-time plus month year days)]
         [forma.matrix.utils :only (sparse-expander)]
         [forma.utils :only (inc-eq? all-unique? contains-nils?)])
   (:require [clj-time.core :as time]

;; (It's important to note that time periods are NOT measured from the
;; activation date of a specific product. The first available NDVI
;; 16-day composite, for example, has a beginning date of February
;; 18th 2001, or ordinal day 49, the 1st day of the 4th period as
;; measured from January 1st. With our reference of January 1st, This
;; dataset will receive an index of 3, and will match up with any
;; other data that falls within that 16-day period. This provides

(def months (partial delta-periods month 1))
(def sixteens (partial delta-periods ordinal 16))
(def eights (partial delta-periods ordinal 8))
(def ones (partial delta-periods ordinal 1))

(defn periodize
  "Converts the supplied `org.joda.time.DateTime` object into a
